the expectancy-value (EV) theory of Fishbein and Ajzen (1975).

October 13, 2012

Beliefs & values related to the attitude towards a item or action

EVT has three basic components. First, individuals respond to novel information about an item or action by developing a belief about the item or action. If a belief already exists, it can and most likely will be modified by new information. Second, individuals assign a value to each attribute that a belief is based on. Third, an expectation is created or modified based on the result of a calculation based on beliefs and values. For example, a student finds out that a professor has a reputation for being humorous. The student assigns a positive value to humor in the classroom, so the student has the expectation that their experience with the professor will be positive. When the student attends class and finds the professor humorous, the student calculates that it is a good class.

Therefore, we have several options for trying to persuade someone. The first group of options are like the strategies identified by information integration theory:

-strengthen the belief strength of an attitude that supports the persuasive goal.
-strengthen the evaluation of an attitude that supports the persuasive goal
-weaken the belief strength of an attitude that opposes the persuasive goal
-weaken the evaluation of an attitude that supports the persuasive goal
-create a new attitude with a belief strength and evaluation that supports the persuasive goal
-remind our audience of a forgotten attitude with a belief strength and evaluation that supports the persuasive goal.

For example, suppose you wanted to persuade your roommate, Pat, to go see a movie. If Pat had a positive attitude toward that movie (“I’ve heard that movie is funny”), you could try to increase the belief strength (“Everyone says it is funny; no question about it”) or evaluation (“That movie isn’t just funny, its hilarious!”) of that attitude. If Pat had a negative attitude toward attending the movie (“The movie theater is decrepit”) you could try to reduce the belief strength (“They remodeled it”) or evaluation (“The important thing is the movie, not the theater”) of that negative attitude. You could create a new favorable attitude (“I heard the soundtrack to this movie is great!”) or remind Pat of a favorable attitude.

However, the addition of subjective norms creates several other options:

-strengthen a normative belief that supports the persuasive goal
-increase the motivation to comply with a norm that supports the persuasive goal
-reduce a normative belief that opposes the persuasive goal
-reduce the motivation to comply with a norm that opposes the persuasive goal
-create a new subjective norm that supports the persuasive goal
-remind the audience of a forgotten subjective norm that supports the persuasive goal.

For example, you could try to strengthen an existing normative belief (“No one should sit home on a Friday night”) or increase the motivation to comply (“You’ll really be depressed if you stay home — people are right when they say you shouldn’t stay home on the weekend”). If Pat thinks it is wrong to go to a movie with a roommate instead of a date, you could try to weaken this normative belief or her motivation to comply with it. Furthermore, you could try to create a new norm (“Everybody is going to see movies made by this director”) or remind Pat of a forgotten norm.